Filesys::Notify::Simple is a simple but unified interface to get
notifications of changes to a given filesystem path. It utilizes
inotify2 on Linux and fsevents on OS X if they're installed, with a
fallback to the full directory scan if they're not available.

There are some limitations in this module. If you don't like it, use
File::ChangeNotify.

    * There is no file name based filter. Do it in your own code.  
    * You can not get types of events (created, updated, deleted).  
    * Currently wait method blocks.

In return, this module doesn't depend on any non-core modules. Platform
specific optimizations with Linux::Inotify2 and Mac::FSEvents are truely
optional.
